Post migration issues

Hello.
I’m used seafile server for 3 years like a standalone app in linux server. After my linux system crashed, i install new Ubuntu 20.04 and tried to start previous installation seafile-server 6.3 (not from system disk). But cannot find some python2 libraries (error in compile MySQL-python) and decide migrate to sefile server in docker.
I’m start docker image, restore 3 mysql table from backup, copy seafile-hub and seafile-data content from previous standalone installation to new /shared folder and restart docker seafile.
Now i can login to seafile with my users and sea all libraries and files. I can see any jpeg image. But i cannot open another type of file (like pdf, avi, md) and cannot download any files (502 http Hello.
I’m used seafile server for 3 years like a standalone app in linux server. After my linux system crashed, i install new Ubuntu 20.04 and tried to start previous installation seafile-server 6.3 (not from system disk). But cannot find some python2 libraries (error in compile MySQL-python) and decide migrate to sefile server in docker.
I’m start docker image, restore 3 mysql table from backup, copy seafile-hub and seafile-data content from previous standalone installation to new /shared folder and restart docker seafile.
Now i can login to seafile with my users and sea all libraries and files. I can see any jpeg image. But i cannot open another type of file (like pdf, avi, md) and cannot download any files (502 http error).
I do not know what to do. How can I recover my files?

Upgrade to 7.x and python 2 won’t be used anymore. Make sure to run all major upgrade script between the old and new version.

Thx for your reply. I understand that seafile server 7.x work only under python3. But i’m migrate from standalone linux seafile server 6.3 to docker seafile server 6.3.
What log file can show me what wrong?

Solved.
Problem in old nginx proxy that rewrite seafhttp requests.